516 SIDNEY POWERS 
Stuert Hill consists of olivine basalt and agglomerate, Pumpkin 
Hill of palagonite tuff of basaltic composition containing fragments 
of coral reef limestone. The tuff with its inclusions is indistinguish- 
able from that which composes the well-known cones on the island 
Oahu, Hawaiian Islands, near Honolulu. Stuert Hill was evidently 
Fic. 3.—Relief map of Guatemala, showing the long Polochie—Lake Izabal Valley 
on the north, Motagua Valley in the center, the row of volcanoes facing the Pacific, 
and the broad plain at the Pacific Coast. The International Railroad runs from 
Puerto Barrios, on the Atlantic, up the Motagua Valley, past Guatemala City in the 
high plateaus to San Jose, on the Pacific. A branch line runs from Santa Maria 
northwestward to the Mexican boundary. 
a center of volcanic activity in Quaternary time—perhaps the 
principal one for the island—while Pumpkin Hill probably resulted 
from a local submarine eruption breaking through coral reefs. 
Small coral reefs are found on the summit of Stuert Hill, and a 
small elevation called Brandon Hill is composed entirely of lime- 
stone. The age of these reefs is unknown, but is probably quite 
